std.Build: changing the default step does silently omit executable installation

[matu3ba]

Zig Version

0.11.0-dev.1893+2770159606

Steps to Reproduce and Observed Output

mkdir repro && cd repro
zig init-exe

2. change build.zig to

const std = @import("std");
pub fn build(b: *std.Build) void {
    const target = b.standardTargetOptions(.{});
    const optimize = b.standardOptimizeOption(.{});
    const reduze_exe = b.addExecutable(.{
        .name = "reduze",
        .root_source_file = .{ .path = "src/main.zig" },
        .target = target,
        .optimize = optimize,
    });
    // 1 does not change install semantics:
    // reduze_exe.install();
    // 2 step with "install" does not work, but with install2 it works:
    const install_art = b.addInstallArtifact(reduze_exe);
    const install_step = b.step("install", "Install reducer executable");
    install_step.dependOn(&install_art.step);

    // omitted to keep things dense
    const reduction_test = b.step("tred", "Run reduction tests");
    reduction_test.dependOn(&reduze_exe.step);
}

Expected Output

Comptime or runtime error to ensure zig build == zig build install in all standard cases.

Personally, with the arrival of the build system and proper caching of generated artifacts, I would prefer to not have zig build == zig build install and rather 1. zig build ONLY builds the help page + checks consistency and zig build install does 1. and 2. installs whatever is given as install steps into zig-out/.

[dweiller]

I guess the issue is that std.Build uses an array list, so it doesn't notice when two steps have the same name, so the root of the problem isn't really related to the install step specifically. An easy fix would be to switch to using a HashMap or ArrayHashMap and have std.Build.step error if you try to clobber a step.